Salazar said in an interview with The Associated Press that the Solyndra Inc. case and a delay in the massive Blythe solar project in California illustrate the challenges facing the solar industry. But he remained upbeat about the potential for solar power. The Obama administration has spent billions of dollars to promote it as part of a push for renewable energy.

“I think the future for solar energy is bright,” Salazar said, predicting that success would come over the next several years and convince even cynics that solar can be an affordable alternative to coal-fired power plants and other traditional forms of energy.

Still, Salazar acknowledged risks, including fierce competition from China and changes in technology that have forced some solar companies out of business.

Solyndra was the first company to receive a loan under an Energy Department program to boost renewable energy companies, receiving more than half a billion dollars; but competition from China and the drying up of recession-battered European markets led it to file for bankruptcy and lay off 1,100 workers.

“It’s not going to be a perfect path where every project proposed is going to be built toward completion,” he said, comparing the Solyndra failure and other high-profile bankruptcies to “dry holes” encountered by early oil and gas explorers.

Salazar, California Gov. Jerry Brown and other elected officials were in attendance in June when Solar Trust of America broke ground on its 1,000-megawatt Blythe solar project in Southern California. The project has been touted as the world’s largest solar power plant and a keystone of the Obama administration’s efforts to promote solar energy.

Last month, the company announced the project was being delayed for at least a year to accommodate a major technology change, from solar thermal troughs to photovoltaic solar panels that convert the sun’s power into electricity.

Salazar called the setback a normal part of the industry’s evolution and said it would not deter him from approving more solar projects.

In the past 18 months, the Interior Department has approved 20 major renewable energy projects, including 13 commercial-scale solar energy plants. The 13 plants together will create about 8,600 construction and operational jobs and produce nearly 5,000 megawatts of energy, enough to power about 1.5 million homes, Salazar said.

Salazar was in Nevada Tuesday to visit the first utility-scale solar power plant built on public lands. The plant, near the California border, is being developed by Arizona-based First Solar and is expected to begin producing energy by the end of the year. The plant is expected to provide enough power for at least 9,000 homes.

The Nevada project will use steel from Indiana, Salazar said, showing how solar energy can benefit the entire country.

Critics who say the administration should not be subsidizing renewable energy companies are wrong, Salazar said, noting that the oil and gas industry has received tax breaks and other incentives for more than a century.

“Those who believe we should turn the clock back” and stop renewable energy subsidies are ceding leadership to China and other countries, he said. “They are accepting a second-place or third-place role for the United States. That’s not what the president is about and it’s not what the Department of Interior is about,” Salazar said.